A randomized trial of abandoned housing remediation, substance abuse and violence Housing abandonment poses a major health burden that has grown significantly over the past several decades in the US. As a typical US city, Philadelphia has some 40,000 vacant properties, a significant number with abandoned residential buildings or structures. Research, including our own, has shown that vacant and abandoned properties are associated with drug- dependence, firearm violence, stress, sexually transmitted diseases, and premature mortality. Our prior research also shows that urban residents see abandoned buildings every day on their way to work or school and describe these undesirable structures as foremost, hypervisible detractors to community health, reducing community cohesion and creating trash, rodents, crime, fear, stress, and havens for transients, drug use, and sex work. Multiple theories posit that visible, environmental disorders, such as abandoned buildings, lead to community decline by signaling that a community is uncared-for, incivilities are tolerated, and the ability of residents to engage in shared expectations of social control over neighborhood problems is eroded. As a result, residents are prevented from engaging in positive health behaviors while unhealthy behaviors, such as substance abuse and violence, become sheltered and more prevalent. Direct remediation of abandoned housing could thus be a potent intervention to interrupt longstanding substance abuse and violence. The proposed research team has produced several preliminary/pilot studies that demonstrate its capacity to complete the proposed study: (1) a published, citywide quasi-experimental study of the health and safety effects of a novel abandoned building remediation protocol stemming from the 2011 Philadelphia Doors and Windows Ordinance; (2) multiple published pilot randomized controlled trials (RCTs) of the effects of abandoned and vacant property remediation on health and safety; and (3) a large, citywide RCT of vacant lot greening involving over 600,000 ft2 of land and a 5-wave, random sample survey of over 600 Philadelphians. There have been no RCTs that test the health and safety effects of abandoned housing remediation. The broad objective of this proposal addressed this gap in knowledge by conducting a citywide RCT of the effects of abandoned housing remediation on substance abuse outcomes, both alcohol and drug related, and violence outcomes, particularly firearm violence. A total of 320 randomly selected abandoned houses, stratified into four geographic sections of Philadelphia, will be randomly assigned to four trial arms: full abandoned housing remediation (n=80, full treatment), graffiti and trash clean-up only (n=80, graffiti treatment), trash clean-up only (n=80, contact control), and no housing remediation or clean-up (n=80, no treatment). Longitudinal outcomes on and near the abandoned houses will be measured in the 18 months before and after treatment. Mixed, quantitative and qualitative methods, will be used to achieve the proposed specific aims in determining if abandoned housing remediation is a cost-effective approach to substance abuse and firearm violence.